Sleeve for reinforcing syringe cartridge

ABSTRACT

An apparatus for transdermal injection includes a sleeve including a proximal end, a distal end, and an inner wall surface extending along the sleeve from a first opening at the proximal end to a second opening at the distal end. The inner wall surface forms a channel in the sleeve, the channel having a first portion with a substantially frustoconical shape. The channel of the sleeve is configured to receive a substantially frustconically shaped injection cartridge, to substantially uniformly support the injection cartridge during a transdermal injection operation, and to prevent movement of the injection cartridge out of the distal end of the sleeve.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/305,569, filed on Mar. 9, 2016, the contents of which are herebyincorporated by reference in their entirety.

FIELD OF INVENTION

This invention relates to delivery of drugs, and in particular, toinjecting drugs through the skin.

BACKGROUND

The skin of organisms such as humans serves as a protective barrierthat, among other functions, prevents pathogens from entering the bodyand prevents or regulates fluids such as blood and water from exitingthe body. In the field of modern medicine, there is often a need todeliver injectates such as drugs through the skin and into thebloodstream of patients. Traditionally, this delivery of liquids into apatient's body is accomplished by insertion of a needle through thepatient's skin and into an area inside of the patient's body where theliquid can enter the patient's blood stream.

However, the use of needles to deliver liquids into a patient's body hasa number of significant drawbacks such as the pain associated with beingpierced by a needle, the fear that many patients have of needles, andthe skin damage and associated risk of infection that occurs due to theuse of needles.

As a result, needle-free transdermal injection devices have beendeveloped. These devices use a high pressure, narrow jet of injectionliquid or powder to penetrate a patient's skin, obviating the need topierce the patient's skin with a needle.

One way to deliver a drug is to place it inside a cylinder having apiston at one end thereof, and to drive the piston impulsively toprovide the necessary pressure to separate the skin cells.Unfortunately, pressure acts in all directions, and in particular, actsagainst the wall of the cartridge. This causes the wall to bow outwardand/or compress, thus increasing the volume of the cartridge andreducing the overall pressure. This deformation is more likely to occurduring periods of rapid acceleration which can lead to imprecisedelivery (i.e., incorrect dosage) and even malfunction. The lostinjection energy and decrease in acceleration of the injectates can also“wetness” (i.e., residual injectate on the skin).

Increasing the thickness of the wall does not prevent deformation of theinner wall of the cartridge (e.g., bending, buckling, or compression).Even relatively thick glass or medical grade plastic cartridges cancompress under certain delivery pressures as those materials are notsufficiently rigid.

SUMMARY

The invention provides a way to reinforce the cartridge so that it cansustain a high pressure impulse with negligible deformation.

In a general aspect, the invention features an apparatus for transdermalinjection. Such an apparatus includes a collet configured to transitionbetween first and second states. In the first state, the collet receivesa cartridge. In the second state, the collet supports the cartridge. Itis noted that the collet described herein does not have all of theproperties of a conventional collet and does not necessarily conform tothe conventional definition of the term ‘collet.’ Indeed, the colletdescribed herein holds and substantially uniformly supports a wall of acartridge to prevent deformation of the wall (e.g., bending, buckling,or compression) when the cartridge is pressurized; a function which isnot performed by conventional collets. Indeed, conventional collets areoften segmented metal bands, collars, ferrules, or flanges which usefriction to hold a tool (e.g., a drill bit) in place. In operation, thesegments of a conventional collet are never fully closed and thereforeconventional collets are incapable of substantially uniformly supportinga wall of a cartridge to prevent deformation of the wall.

In some embodiments, the collet comprises first and second legs, each ofwhich has an inner surface that defines a recess that conforms to acartridge. The two legs pivot during transition of the collet betweenits two states. Among these embodiments are those in which the recessaccommodates a frustoconical surface. Also among these embodiments arethose in that include pivots inserted through distal ends of the legs,those in which the legs each comprise a straight proximal section and atapered distal section, those in which the legs drive a cartridgedistally direction as the collet transitions from the first to thesecond state, those in which, when the collet is in its second state,the recesses of the first and second leg collectively support everypoint on an outer wall of the cartridge, and those in which fingers movealong lines parallel to an axis of the collet and cause the transitionas they do so. Among these embodiments with fingers are those in which,as the fingers climb the legs, the collet transitions into the secondstate.

Yet other embodiments include fingers that move along lines parallel toan axis of the collet. In these embodiments, the fingers cause thetransition as they move.

Some embodiments include a yoke, with fingers for engaging legs of thecollet being constituents of this yoke.

Also among the embodiments are those in which, when the collet is in thesecond state, the cartridge is flush with a distal end of the collet.

In another general aspect, a method for carrying out a transdermalinjection includes loading a cartridge having a predetermined elongateshape into a collet which defines a chamber for supporting an injectablematerial, causing the collet to transition into a state in which thecollet substantially conforms to the predetermined elongate shape of thecartridge such that, upon pressurization of the cartridge, expansion ofthe cartridge is substantially uniformly opposed, and applying pressureat a proximal end of the cartridge, thereby pressurizing the cartridgeand causing ejection of the injectable material from a distal end of thecartridge.

Aspects may include one or more of the following features.

The collet may include first and second legs, the legs each having aninner surface that defines a recess configured to substantially conformto the predetermined elongate shape of the cartridge. The first andsecond legs may be configured to pivot during transition of the colletbetween the first and second states. Causing the collet to transition into the state in which the collet supports substantially all points onthe outer wall of the cartridge may include moving fingers along anouter surface of the collet in a direction parallel to an axis of thecollet, thereby causing the legs to pivot into the state.

A ratio of a length of the cartridge to the width of the cartridge maybe 10 to 1. A ratio of a length of the cartridge to the width of thecartridge may be 50 to 1. The cartridge may include an outer wall and aninner wall, and in the state the collet may support substantially allpoints on the outer wall of the cartridge. A distance between the outerwall of the cartridge and the inner wall of the cartridge may be in arange of 0.5 mm to 6 mm. The predefined shape of the cartridge may be asubstantially frustoconical shape.

In another general aspect, a method for carrying out a transdermalinjection includes the following steps. A cartridge is loaded into acollet, the cartridge having an outer wall and an inner wall, whichdefines a chamber for supporting an injectable material. The collet iscaused to transition into a state in which the collet supports allpoints on the outer wall of the cartridge. An impulse of pressure isapplied at a proximal end of the cartridge, thereby causing ejection ofthe injectable material from a distal end of said cartridge.

In yet another general aspect, an apparatus for transdermal injectionincludes a sleeve including a proximal end, a distal end, and an innerwall surface extending along the sleeve from a first opening at theproximal end to a second opening at the distal end. The inner wallsurface forms a channel in the sleeve, the channel having a firstportion with a substantially frustoconical shape. The channel of thesleeve is configured to receive a substantially frustconically shapedinjection cartridge, to substantially uniformly support the injectioncartridge during a transdermal injection operation, and to preventmovement of the injection cartridge out of the distal end of the sleeve.

Aspects may include one or more of the following features.

The sleeve may include a stop edge disposed at the distal end, the stopedge being configured to prevent movement of the injection cartridge outof the distal end of the sleeve. The channel may include a secondportion extending from the second opening to the first portion of thechannel, the second portion having a substantially cylindrical shape.The sleeve may include a ring disposed in the second portion of thechannel, the ring having a hole with a first inner diameter smaller thana second inner diameter of a distal end of the first portion of thechannel and forming the stop edge at a point in the channel where thefirst portion and the second portion meet.

The ring may be press fit into the second portion of the channel. Thering may be welded into the second portion of the channel. The ring maybe fixed in the second portion of the channel using an adhesive. Aportion of an outer wall surface adjacent to the sleeve proximal end mayinclude threads. A diameter of the first portion of the channel maytaper from a first diameter in a range of 7 mm to 8 mm to a seconddiameter in a range of 6 mm to 7 mm.

A thickness of a wall of the sleeve adjacent to the first portion of thechannel may be in a range of 0.5 mm to 5 mm. The sleeve may be formedfrom a stainless steel material.

In yet another general aspect, an apparatus for transdermal injectionincludes a cartridge including a proximal end, a distal end, an outerwall surface, an inner wall surface, and an injection nozzle disposed atthe distal end of the cartridge. The outer wall surface extends betweenthe proximal end and the distal end and has a substantiallyfrustoconical shape. The inner wall surface extends from a first openingat the proximal end and in a direction from the proximal end to thedistal end and forms a channel in the cartridge. The channel has a firstportion with a substantially cylindrical shape and a second portion withthe injection nozzle disposed therein.

Aspects may include one or more of the following features.

The second portion may be configured to receive the injection nozzle andmay include a stop edge configured to prevent the injection nozzle fromexiting the cartridge from the distal end. The injection nozzle may beaffixed in the second portion using an adhesive. The injection nozzlemay be affixed in the second portion using a welding technique. Theinjection nozzle may be integrally formed in the second portion.

The cartridge may include a plunger disposed in the first portion of thechannel. A diameter of the outer wall surface may taper from a firstdiameter in a range of 7.5 mm to 8 mm to a second diameter in a range of6 mm to 6.5 mm. A thickness of a wall of the cartridge along the firstportion of the channel may be in a range of 0.05 mm to 6 mm. Thecartridge may be formed from a plastic material. The apparatus mayinclude a Luer connector disposed at the distal end.

In yet another general aspect, an apparatus for transdermal injectionincludes a sleeve including a sleeve proximal end, a sleeve distal end,and a sleeve inner wall surface extending along the sleeve from a firstopening at the sleeve proximal end to a second opening at the sleevedistal end. The sleeve inner wall surface forms a channel in the sleeve,the channel having a first portion with a substantially frustoconicalshape. The apparatus also includes a cartridge for insertion into thechannel of the sleeve. The cartridge includes a cartridge proximal end,a cartridge distal end, and a cartridge outer wall surface extendingbetween the cartridge proximal end and the cartridge distal end. Thecartridge outer wall surface has a substantially frustoconical shapeconforming to the first portion of the channel. The sleeve inner wallsurface is configured to substantially uniformly support the cartridgeouter wall surface during an injection operation.

BRIEF DESCRIPTION OF THE FIGURES

These and other features and advantages of the invention will beapparent from the following detailed description and the accompanyingfigures, in which:

FIG. 1A shows a first embodiment of an injection apparatus in a fullyopen position for receiving a cartridge;

FIG. 1B shows a cross section of a leg of the apparatus of FIG. 1A;

FIG. 2A shows the apparatus of FIG. 1A in an intermediate position withthe fingers having climbed part way up the leg;

FIG. 2B shows a cross-section of the apparatus when the fingers haveclimbed to the position shown in FIG. 2A;

FIG. 3A shows the apparatus of FIG. 1A when the fingers have justreached the straight section of the leg;

FIG. 3B shows a cross-section of the apparatus when the fingers arepositioned as shown in FIG. 3A;

FIG. 4A shows the apparatus of FIG. 1A when the legs are in the fullyclosed position;

FIG. 4B shows a cross-section of the apparatus when the legs are in thefully closed position as shown in FIG. 4A;

FIG. 5 shows a cross-section of a second embodiment in a fully closedposition, generally corresponding to FIG. 3A;

FIG. 6 shows a cross-section of the second embodiment of FIG. 5 in thefully closed position with the cartridge being forced in a directionaway from the pivots 112A-B;

FIG. 7 is a cross-section of a third embodiment, shown in a partiallyclosed position;

FIG. 8 is a cross-section of the embodiment of FIG. 6, in the closedposition;

FIG. 9 is a perspective view of the third embodiment in a partially openposition corresponding to FIG. 7; and

FIG. 10 is a perspective view of the third embodiment in a fully closedposition corresponding to FIG. 8.

FIG. 11 is representative data showing load versus cartridge deformationfor a thin-walled plastic cartridge with a collet as well as for athick-walled stainless steel cartridge.

FIG. 12 is a fourth embodiment in an assembled state.

FIG. 13 is a reinforcing sleeve of the fourth embodiment of FIG. 12.

FIG. 14 is a cartridge of the fourth embodiment of FIG. 12.

FIG. 15 is a fifth embodiment in an assembled state.

DETAILED DESCRIPTION I. First Embodiment

As shown in FIG. 1A, an apparatus for transdermal injection includes acartridge 120 for holding an injectable substance (e.g., drug) to bedelivered through the skin. The cartridge has a wall 122 having aproximal end and a distal end, with the proximal end being wider thanthe distal end. Between the proximal and distal end, the wall 122defines an approximately frustoconical section about an axis 105. Theproximal end receives a piston for delivering a pressure impulse and thedistal end is placed against the patient's skin.

For purposes of discussion, it is useful to define a cylindricalcoordinate system and to define first and second sections of thecartridge 120. A first section is the set of points that are on theouter surface of the cartridge 120 and that have a circumferentialcoordinate between 0° and 180°. A second section is the set of points onthe outer surface of the cartridge 120 that are not in the first set ofpoints.

The apparatus further includes a collet having a first leg 110B and asecond leg 110A.

The first leg 110B has a proximal end and a distal end. A first pivotpoint 112B passes through a foot at the distal end of the first leg110B. As a result, the first leg 110B can pivot between an openposition, as shown in FIG. 1A, and a closed position, as shown in FIG.4A.

Between its proximal and distal ends, the first leg 110B has an outersurface that defines a straight section and a tapered section. Thestraight section is that portion of the first leg 110B for which theouter surface is parallel to the axis 105 when the first leg 110B is inthe closed position shown in FIG. 4A. The tapered section is one inwhich the outer surface defines a line that slopes toward the axis 105so that the outer surface is closest to the axis 105 at the distal endof the first leg 110B and furthest from the axis at the proximal end ofthe first leg 110B.

The first leg 110B engages a vertically-moving first finger 132B thatmoves along a line parallel to the axis 105. When the first leg 110B isin its open position, as shown in FIG. 1A, the first finger 132B engagesthe distalmost portion of the first leg's tapered section. When thefirst leg 110B is in its closed position, as shown in FIG. 4A, the firstfinger 132B engages the proximal end of the first leg 110B. It isapparent therefore that as the first finger 132B moves from the distalend to the proximal end, it causes the first leg 110B to pivotcounter-clockwise.

Referring now to FIG. 1B, the first leg 110B has a cross section thatfeatures a recess. This recess is shaped to conform exactly to thefrustoconical shape of the cartridge 120. As a result, when the firstleg 110A is in the fully closed position shown in FIG. 4B, the cartridgeis fully nestled within the recess so that the recess supports allpoints in the first section of the cartridge 120.

The collet's a second leg 110A has a proximal end and a distal end. Asecond pivot point 112A passes through a foot at the distal end of thesecond leg 110A. As a result, the second leg 110A can pivot between anopen position, as shown in FIG. 1A, and a closed position, as shown inFIG. 4A.

Between its proximal and distal ends, the second leg 110A has an outersurface that defines a straight section and a tapered section. Thestraight section is that portion of the second leg 110A for which theouter surface is parallel to the axis 105 when the second leg 110A is inthe closed position shown in FIG. 4A. The tapered section is one inwhich the outer surface defines a line that slopes toward the axis 105so that the outer surface is closest to the axis 105 at the distal endof the second leg 110A and furthest from the axis at the proximal end ofthe second leg 110A.

The second leg 110A engages a second vertically-moving second finger132A that moves along a line parallel to the axis 105. When the secondleg 110A is in its open position, as shown in FIG. 1A, the second finger132A engages the distalmost portion of the second leg's tapered section.When the second leg 110A is in its closed position, as shown in FIG. 4A,the second finger 132A engages the proximal end of the second leg 110A.It is apparent therefore that as the second finger 132A moves from thedistal end to the proximal end, it causes the second leg 110A to pivotclockwise.

Referring now to FIG. 1B, the second leg 110A has a cross section thatfeatures a recess. This recess is shaped to conform exactly to thefrustoconical shape of the cartridge 120. As a result, when the secondleg 110A is in the fully closed position shown in FIG. 4B, the cartridgeis fully nestled within the recess so that the recess supports allpoints in the second section of the cartridge 120.

It is apparent therefore that when the first and second legs 110A, 110Bare in the fully closed position as shown in FIG. 4A, the entire surfaceof the cartridge 120 is fully supported, as shown in FIG. 4B. As aresult, when a pressure impulse is applied, deformation and/orcompression of the walls of cartridge 120 are minimized.

In some embodiments, as shown in FIG. 4B, the first and second fingers132B, 132A are arms of a single yoke 132 that travels along a pathparallel to the axis 105. This is particularly advantageous since thefingers 132B, 132A will inherently be moved together.

A particular advantage of having a leg with both a straight section anda tapered section is that once the fingers 132A, 132B are on thestraight section, a distally directed force as shown in FIG. 4A willhave no effect on the fingers 132A, 132B. In contrast, had the taperedsection continued all the way to the proximal end of the leg 110A, 110Bso that there is no straight section, then a distally directed forcecould be resolved into a component that would tend to force the fingers132A, 132B distally.

As shown in FIG. 4A, the distal tip of the cartridge is flush with thedistal tips of the legs 110A, 110B so that it can contact the skin ofthe patient. This state is reached gradually as the fingers 132A, 132Bare moved towards the proximal end of the legs 110A, 110B. As shown inFIG. 2A, with the legs part way up to the straight section, thecartridge 120 is considerably more distal than it was in FIG. 1A. FIG.2B is a cross section showing that a considerable air gap remainsbetween the cartridge 120 and the walls of the recesses.

In FIG. 3A, the fingers 132A, 132B have moved all the way to thebeginning of the legs' straight sections. In this position, the firstand second legs 110A, 110B have now made contact at the level of thefingers 132A, 132B as shown in FIG. 3B. However, the distal tip of thecartridge 120 is not yet aligned with the distal tips of the legs 110A,110B.

As the fingers 132A, 132B move further in the distal direction, the legs110A, 110B continue to force the cartridge 120 in the distal direction.By the time the fingers 132A, 132B have reached the top of the straightsection, the distal end of the cartridge 120 will have become alignedwith the distal end of the legs 110A, 110B so that an injection can begiven.

Fingers 132A, 132B can be moved manually or by an actuator (e.g.,motor).

The cartridge may be made of a plastic, glass or metal. For example, thecartridge is made of a medical-grade plastic having a thin wall and aflange. In another embodiment, the cartridge is in the form of anampoule having a wall thickness in a range between 0.05 mm and 6 mm

In the embodiment described above in conjunction with FIGS. 1A through4B, legs having tapered surfaces were used with a counterpart taperedcartridge. Other mechanisms for engaging and providing reinforcingsupport for the cartridge are also applicable including retention clips,surface grips, interlocking interfaces and tension devices can be used.

II. Second Embodiment

Another embodiment is illustrated in FIGS. 5-10. Generally, in theembodiment of FIGS. 1A-4B, the cartridge is inserted in one direction asshown in FIGS. 1A-3A, and then forced in the same direction as shown inFIG. 4A. In this other embodiment, the cartridge is inserted in onedirection, as shown in FIG. 5, but then forced in the directionopposite, as shown in FIG. 6. Therefore, the direction of the taper ofthe cartridge 220 of FIGS. 5-10 is opposite to the direction of taper ofcartridge 110 of FIGS. 1A-4B. Similarly, the corresponding taper on thelegs 210A-B is opposite to the taper on the legs 110A-B.

III. Third Embodiment

FIGS. 7-10 show another version of the embodiment of FIGS. 5-6, with theelements labeled with same reference numerals to show the correspondenceof the parts. FIGS. 7 and 9 show this version in a partially openposition, and FIGS. 8 and 10 show this version in the closed position.

A preliminary study was conducted to investigate the effect ofsupporting a thin-walled plastic cartridge with a collet on cartridgedeformation, compared to the deformation of a thick-walled stainlesssteel cartridge. Three cartridges were subjected to an increasing loadranging from 100 N to 700 N and the output cartridge deformation (mm)was recorded.

Referring to FIG. 11, the data shows increased compliance in anuncollected thick-walled polycarbonate cartridge, compared to anuncollected thick-walled stainless steel cartridge, and a decrease incartridge compliance of a thin-walled polycarbonate cartridge upon theaddition of a supporting collet. It should be understood that there arenumerous other alternative embodiments. For example, rather than 2 legs,N>2 (e.g., 3, 4, etc.) legs may be used to hold the cartridge. Also,various methods of mechanically biasing or forcing the legs to theclosed position may be used. For example, the pivots 132A-B may havetorsional springs coupled to them to bias the legs. In some embodiments,the force that pushes the cartridge along or opposite to the directionof insertion (e.g., as shown in FIGS. 4A and 6) may result whileapplying pressure to the fluid in the cartridge during the process ofexpelling the fluid from the cartridge. For example, in FIG. 4, forcemay be applied to pressurize the fluid via the end of the cartridgedistant from the pivots 112A-B, and fluid expelled at the end of thepivots, and this force causes the taper of the cartridge 120 to engagethe taper of the legs 110A-B. As another example, in FIG. 6, force topressurize the fluid is applied at the end of the cartridge 220 near thepivots 112A-B, and the fluid is ejected at the other end of thecartridge, and this force causes the cartridge to engage the taper ofthe legs 210A-B.

IV. Fourth Embodiment

Referring to FIG. 12, in another embodiment, an injector head assembly1200 includes a cartridge 1202 inserted into a reinforcing sleeve 1204.The cartridge 1202 is configured to hold an injectate for deliverythrough a patient's skin. The cartridge 1202 has a relatively thin wallswhich are susceptible to deformation (e.g., ballooning) when theinjectate in the cartridge 1202 is pressurized. The reinforcing sleeve1204 is a rigid member configured to receive and support the cartridge1202 such that deformation of the cartridge 1202 is substantiallyprevented during an injection operation.

a. Reinforcing Sleeve

Referring to FIG. 13, the reinforcing sleeve 1202 is an elongate,substantially cylindrical member formed from a rigid material such asstainless steel. The reinforcing sleeve 1204 has a sleeve proximal end1306 having a sleeve proximal end opening 1308 and a sleeve distal end1310 having a sleeve distal end opening 1312. A first channel 1314 isdefined by an inner surface 1315 of the reinforcing sleeve 1204 andextends along a length of the reinforcing sleeve 1204 from the sleeveproximal end opening 1308 to the sleeve distal end opening 1312. Thefirst channel 1314 has a cartridge receiving portion 1316 and a ringreceiving portion 1318.

The cartridge receiving portion 1316 extends from the sleeve proximalend opening 1308 to a first channel transition point 1320. A diameter ofthe cartridge receiving portion 1316 tapers substantially linearly froma first diameter, D₁ at the proximal end 1306 of the reinforcing sleeve1204 to a second, smaller diameter, D₂ near at the first channeltransition point 1320, resulting in the cartridge receiving portion 1316having a substantially frustoconical shape. In some examples, the firstdiameter, D₁ is in a range of 7 mm to 8 mm (e.g., 7.887 mm). In someexamples, the second diameter, D₂ is in a range of 6 mm to 7 mm (e.g.,6.04 mm).

The ring receiving portion 1318 extends from the first channeltransition point 1320 to the sleeve distal end opening 1312. A diameter,D₃ of the ring receiving portion 1318 is greater than the seconddiameter, D₂. A shoulder 1322 is formed at the channel transition point1320 due to an abrupt change in the diameter of the first channel 1314from the second diameter, D₂ to the third diameter, D₃. In someexamples, the third diameter, D₃ is in a range of 7.938 mm to 8.326 mm.

The ring receiving portion 1318 of the channel 1314 is configured tofixedly receive a ring 1324. In some examples, the ring 1324 is pressfit into the ring receiving portion 1318 such that it rests against theshoulder 1322 and is substantially flush with the sleeve distal end1306. In other examples, the ring 1324 is glued, welded, or otherwiseaffixed in the ring receiving portion 1318. An injection channel 1326extends through the ring 1324 and permits ejection of injectate from theinjector head assembly 1200.

In some examples, the sleeve proximal end 1306 includes threads 1328 forconnecting the reinforcing sleeve 1204 to an injector mechanism (notshown). In some examples, the distal end 1310 of the reinforcing sleeve1204 includes a flared portion 1330 for interfacing with one or moreinjector head accessories.

In some examples, the reinforcing sleeve 1204 is formed from a sheetmetal material. In some examples, a wall 1380 adjacent to the cartridgereceiving portion 1316 has a maximum thickness in the range of 0.5 mm to5 mm and a minimum thickness in the range of 0.5 mm to 5 mm.

While specific ranges of diameters and thicknesses are provided for thereinforcing sleeve 1204, it should be noted that the diameters andthicknesses are generally configurable to accommodate a cartridge of anysize, as long as the substantially frustoconically shaped cartridgereceiving portion of the sleeve conforms to the cartridge.

Referring to FIG. 14, the cartridge 1202 is an elongate, substantiallyfrustoconically shaped member formed as a container with relative thinplastic walls 1482. The cartridge 1202 has a cartridge proximal end 1432and a cartridge distal end 1434. An outer surface 1436 of the cartridge1202 extends along a length of the cartridge 1202 from the cartridgeproximal end 1432 to the cartridge distal end 1434. A diameter of theouter surface 1436 of the cartridge 1202 tapers substantially linearlyfrom a fourth diameter, D₄ to a fifth, smaller diameter, D₅, resultingthe outer surface 1436 of the cartridge 1202 having a substantiallyfrustoconical shape. In general, the fourth diameter D₄ is slightlylarger than the first diameter, D₁ of the cartridge receiving portion1316 of the first channel 1314 and the fifth diameter, D5 is slightlylarger than the second diameter, D2 of the cartridge receiving portion1316 of the first channel 1314. In some examples, the fourth diameter,D₄ is in a range of 7.5 mm to 8 mm. In some examples, the fifthdiameter, D₅ is in a range of 6 mm to 6.5 mm.

The cartridge proximal end 1432 includes a cartridge proximal endopening 1438 and the cartridge distal end 1434 includes a cartridgedistal end opening 1440. A second channel 1442 is defined by an innersurface 1444 of the cartridge 1202 and extends along a length of thecartridge 1202 from the cartridge proximal end opening 1438 to thecartridge distal end opening 1440. The second channel 1442 includes aplunger receiving portion 1446 (i.e., a bore) and a nozzle receivingportion 1448.

The plunger receiving portion 1446 extends from the cartridge proximalend opening 1438 to a second channel transition point 1450. The plungerreceiving portion 1446 has a substantially constant, sixth diameter, D₆along its length, resulting in the plunger receiving portion 1446 havinga substantially cylindrical shape. In some examples, the sixth diameter,D₆ is in a range of 5 mm to 6 mm. In general, the sixth diameter, D6depends on and is made to conform to the actuation system (e.g., theinjector mechanism) being used.

The nozzle receiving portion 1448 extends from the second channeltransition point 1450 to the cartridge distal end opening 1440. Thenozzle receiving portion 1448 includes a second shoulder 1452 configuredto mate with an injection nozzle 1454 such that the injection nozzle1454 is properly seated in the nozzle receiving portion 1448 and isprevented from exiting the cartridge 1202 via the cartridge distal endopening 1440.

In FIG. 14, the injection nozzle 1454 is shown received in the nozzlereceiving portion 1448. In some examples, the injection nozzle 1454 isaffixed (e.g. glued or welded) in the nozzle receiving portion 1448. Insome examples, the injection nozzle 1454 is integrally formed in thenozzle receiving portion 1448 (e.g., the injection nozzle 1454 is formedduring injection molding of the cartridge 1202).

A plunger 1456 is disposed in the plunger receiving portion 1446 of thesecond channel 1442. In general, movement of the plunger 1456 along theplunger receiving portion 1446 is substantially unimpeded due to theconstant sixth diameter, D₆ of the plunger receiving portion 1446.

In some examples, the walls 1482 of the cartridge 1202 in a region alongthe plunger receiving portion 1446 have a maximum thickness in the rangeof 0.6 mm to 1.2 mm and a minimum thickness in the range of 0.5 mm to0.6 mm.

b. Assembly and Operation

Referring again to FIG. 12, to assemble the injector head assembly 1200,the cartridge 1202 is inserted into the cartridge receiving portion 1316of the first channel 1314 of the reinforcing sleeve 1204. The outersurface 1436 of the cartridge 1202 has a shape corresponding to thecartridge receiving portion 1316 of the first channel 1314 such that thecartridge 1202 can be easily placed in the cartridge receiving portion1316. However, due to the slight differences in diameters, between theouter surface 1436 of the cartridge 1202 and the cartridge receivingportion 1316, the cartridge 1202 cannot be fully inserted into thecartridge receiving portion 1316 without application of force. This isan intentional feature since forcing the cartridge 1202 into thecartridge receiving portion 1316 causes a slight compression of thecartridge 1202, ensuring that the outer surface 1436 of the cartridge1202 is substantially uniformly supported by the inner surface 1315 ofthe cartridge receiving portion 1316 of the first channel 1314.

Therefore, to finalize the assembly of the injector head assembly 1200,a force is applied to the cartridge 1202 and/or the reinforcing sleeve1204, causing the cartridge 1202 to move into the cartridge receivingportion 1316 of the first channel 1314 until the distal end 1434 of thecartridge 1202 makes contact with the first shoulder 1322 of thecartridge reinforcing sleeve 1204.

Once assembled, the injector head assembly 1200 is attached to aninjector to perform an injection operation. To perform the injectionoperation, an actuator causes the plunger 1456 to move through theplunger receiving portion 1446 of the second channel 1442 in a directionfrom the proximal end 1432 of the cartridge 1202 toward the distal end1434 of the cartridge 1202. The movement of the plunger 1456 causes anincreased pressure in injectate present in the plunger receiving portion1446 of the second channel 1442, which in turn causes ejection ofinjectate from the injector head assembly 1200 via the injection nozzle1454 and the injection channel 1326.

The reinforcing sleeve 1204 substantially fully supports the cartridgeand prevents deformation of the cartridge 1202 due to the pressurizationof the injectate in the cartridge 1202. Furthermore, little to nocompression of the relatively thin plastic walls of the cartridge occurssince a majority of force applied to the cartridge walls is transferredthrough the walls to the rigid reinforcing sleeve 1204.

Thus, during an injection operation, as plunger 1454 moves through theplunger receiving portion 1446 of the second channel 1442, pressurerises in the plunger receiving portion 1446. Pressure is exerted on thewall 1482 of cartridge 1202 but the reinforcing sleeve 1204 prevents thepressure from deforming wall 1482 of cartridge 1202. In some examples,the pressure also causes compression of the wall 1482 of cartridge 1202,but the compression is minimal due to thin walls. The first shoulder1322 formed by the ring 1324 in the ring receiving portion 1318 of thefirst channel 1314 prevents the distal end 1434 of the cartridge 1202from separating from the cartridge 1202 and being ejected from thereinforcing sleeve 1204.

V. Fifth Embodiment

Referring to FIG. 15, in another embodiment, an injector head 1500includes a reinforcing sleeve 1504 with a cartridge 1502 disposedtherein. The injector head assembly 1500 has a similar configuration tothe injector head assembly of FIG. 12. One difference however is thatthe cartridge 1502 of FIG. 15 has a Luer type connector 1584 disposed atits distal end 1534. The Luer connector 1584 is configured to receive acorresponding part of a syringe (not shown) for filling the cartridge1502 with injectate.

Having described the invention, and a preferred embodiment thereof, whatis claimed as new, and secured by Letters Patent is:
 1. An apparatus fortransdermal injection, said apparatus comprising: a sleeve including aproximal end, a distal end, and an inner wall surface extending alongthe sleeve from a first opening at the proximal end to a second openingat the distal end, the inner wall surface forming a channel in thesleeve, the channel having a first portion with a substantiallyfrustoconical shape, wherein the channel of the sleeve is configured toreceive a substantially frustconically shaped injection cartridge, tosubstantially uniformly support the injection cartridge during atransdermal injection operation, and to prevent movement of theinjection cartridge out of the distal end of the sleeve.
 2. Theapparatus of claim 1 wherein the sleeve further comprises a stop edgedisposed at the distal end, the stop edge being configured to preventmovement of the injection cartridge out of the distal end of the sleeve.3. The apparatus of claim 2 wherein the channel includes a secondportion extending from the second opening to the first portion of thechannel, the second portion having a substantially cylindrical shape. 4.The apparatus of claim 3 further comprising a ring disposed in thesecond portion of the channel, the ring having a hole with a first innerdiameter smaller than a second inner diameter of a distal end of thefirst portion of the channel and forming the stop edge at a point in thechannel where the first portion and the second portion meet.
 5. Theapparatus of claim 4 wherein the ring is press fit into the secondportion of the channel.
 6. The apparatus of claim 4 wherein the ring iswelded into the second portion of the channel.
 7. The apparatus of claim4 wherein the ring is fixed in the second portion of the channel usingan adhesive.
 8. The apparatus of claim 1 wherein a portion of an outerwall surface adjacent to the sleeve proximal end includes threads. 9.The apparatus of claim 1 wherein a diameter of the first portion of thechannel tapers from a first diameter in a range of 7 mm to 8 mm to asecond diameter in a range of 6 mm to 7 mm.
 10. The apparatus of claim 1wherein a thickness of a wall of the sleeve adjacent to the firstportion of the channel is in a range of 0.5 mm to 5 mm.
 11. Theapparatus of claim 1 wherein the sleeve is formed from a stainless steelmaterial.
 12. An apparatus for transdermal injection, said apparatuscomprising: a cartridge including a proximal end, a distal end, an outerwall surface, an inner wall surface, and an injection nozzle disposed atthe distal end of the cartridge, wherein the outer wall surface extendsbetween the proximal end and the distal end and has a substantiallyfrustoconical shape, the inner wall surface extends from a first openingat the proximal end and in a direction from the proximal end to thedistal end and forms a channel in the cartridge, the channel having afirst portion with a substantially cylindrical shape and a secondportion with the injection nozzle disposed therein.
 13. The apparatus ofclaim 12 wherein the second portion is configured to receive theinjection nozzle and includes a stop edge configured to prevent theinjection nozzle from exiting the cartridge from the distal end.
 14. Theapparatus of claim 13 wherein the injection nozzle is affixed in thesecond portion using a welding technique.
 15. The apparatus of claim 12wherein the injection nozzle is integrally formed in the second portion.16. The apparatus of claim 12 wherein the cartridge includes a plungerdisposed in the first portion of the channel.
 17. The apparatus of claim12 wherein a diameter of the outer wall surface tapers from a firstdiameter in a range of 7.5 mm to 8 mm to a second diameter in a range of6 mm to 6.5 mm.
 18. The apparatus of claim 12 wherein a thickness of awall of the cartridge along the first portion of the channel is in arange of 0.05 mm to 6 mm.
 19. The apparatus of claim 12 wherein thecartridge is formed from a plastic material.
 20. An apparatus fortransdermal injection, said apparatus comprising: a sleeve including asleeve proximal end, a sleeve distal end, and a sleeve inner wallsurface extending along the sleeve from a first opening at the sleeveproximal end to a second opening at the sleeve distal end, the sleeveinner wall surface forming a channel in the sleeve, the channel having afirst portion with a substantially frustoconical shape; and a cartridgefor insertion into the channel of the sleeve, the cartridge including acartridge proximal end, a cartridge distal end, and a cartridge outerwall surface extending between the cartridge proximal end and thecartridge distal end, the cartridge outer wall surface having asubstantially frustoconical shape conforming to the first portion of thechannel; wherein the sleeve inner wall surface is configured tosubstantially uniformly support the cartridge outer wall surface duringan injection operation.